Generally, a door is operated by pushing or pulling. A lateral side of a door is hinged to a doorframe. The door is opened by a pushing force. However in pushing the door, a front side of the door must leave a greater space for operation. If the space is small, it is difficult to install the door and the doorplate is difficult to be opened due to the limitation of the space, or the opening of the door is limited, even the doorplate will collide with other objects. Thus, transversal movement doorplates are developed for resolving above difficulty in the prior art.
Referring to U.S. Pat. No. 5,301,468, “Sliding door”, a prior art door is disclosed in that patent. In the prior art, an upper side of each of two doorplates is installed with a sliding unit. The sliding unit includes a retaining seat and a movable seat. The retaining seat is retained to the doorplate. The retaining seat is formed with a protruded track and a recessed track. The moveable seat is assembled to another doorplate. Each of an upper side and a lower side of the movable seat is installed with a pulley set. The pulley sets are installed to the protruding track and the recessed track so that the moveable seat is slideable with respect to the retaining seat. Thus the doorplate with the moveable seat is moveable transversally with respect to another doorplate.
However although this prior art transversal doorplate may be opened or closed transversally, its structure is very complicated. Furthermore, in the installation thereof, one side of the sliding unit will be over the doorplate with a great size. As a result, the doorplate with the moveable seat has a center of gravity which is shifted to an outer side of the doorplate and thus is distanced to a vertical central line of the doorplate. Therefore, as the connection of the retaining seat and the doorplate is used as a fulcrum, the greater the center of gravity of another doorplate shifted from the central portion, the greater the torque from the weight of the doorplate so that the pressure applied to the protruding track at an upper side of the doorplate is greater. As a result, the burden to the retaining seat is increased. The user will feel a resisting force existed as the user pulls the doorplate. Furthermore, it is possible that the doorplate will turn over. Thus it is unsafe and unbeautiful. Furthermore, to have a beautiful outlook, more and more glass doorplates are used to replace wood doorplate, but glass is heavy than wood so that as glass doorplate will increase the possibility that the doorplate turnovers. Furthermore, the sizes of the retaining seat and the moveable seat are fixed. They are not matched to doorplates of different thicknesses. A sliding device is only suitable for a doorplate of a single thicknesses. Thus it is not practical and necessary to be improved.